The present invention relates generally to an accessory drive for the end of a shaft, said accessory drive being of the type comprising a belt pulley, a carrier, and at least a first and a second planet wheel that are strongly coupled togehter and which have differing numbers of teeth (i.e., differing gear radii). In such a device, the first planet wheel is in engagement with a first gear circulating along with the shaft, and the second planet wheel with a second gear that is rotatable relative to the shaft. A selectively actuable brake is provided between a fixed, stationary part and a part capable of relative rotation. A freewheel prevents backward relative rotation of the second gear with respect to the shaft end, with the first and second gears are arranged radially inside the carrier.
An accessory drive of this kind is known from EP-A 0 301 704, which corresponds to U.S. Pat. No. 4,862,770 (the contents of which are incorporated herein by reference). When the brake is released, the entire torque of the shaft end is transferred through the freewheel, which can lead to severe wear and a diminution in service life. In addition, the belt pulley precedes the planet wheel and the brake in the axial direction. This undesirably results in a large overall axial length.
There remains a need to further develop an accessory drive mechanism of this general type such that it is both substantially more robust and has a reduced overall length in the axial direction.